Adjustable flow control



March 22, 1960 v. STREETER 2,929,402

ADJUSTABLE FLOW CONTROL Filed July 30, 1954 3 Sheets-Sheet l Q i m 0- n GN UPPER RANGE \J RANGE I we h (Ps EXTENDED com-Rot. RANGE FIG 6 a,

FIG. 5

INVENTOR VICTOR L. ETREETEK M Y llTTORNEYf:

Maw}! 2 1 v. STREETER 2,929,402

ADJUSTABLE FLOW CONTROL Filed July 30. 1954 3 Sheets-Sheet 3 \5 /l "l 9 \lb FIG. 9

FIG. 10

INVENTOR VICTOR L. STREETER BY 4a,, Momma United ADJUSTABLE FLOW CONTROL Victor L. Streeter, Chicago, Ill., assignor to The Dole Valve Company, Chicago, 11]., a corporation of Illinois Application July 30, 1954, Serial No. 446,867

Claims. (Cl. 137-517) so that fluid flow may be maintained at a substantially constant adjusted rate substantially irrespective of fluid pressure.

In the development of fluid flow control devices, such as water valves and the like, there has been a constant effort, on the part of the industry, to provide such a device which will have a substantially constant flow rate characteristic substantially independent of the fluid pres sure or head at the inlet to the device or the fluid pressure drop across the device.

As an example, in the development of hot liquid valves, such as those varying through the range of from car heater valves to shower bath valves, it has been found to be most desirable to have a valve structure through which the liquid flow rate will be substantially constant irrespective of the pressure drop across the valve. Further, of course, it is also highly desirable to provide such a valve structure with means to adjust the flow rate therethrough to any particularly desired flow rate within the design range of the valve and to then have that selected flow rate maintained substantially constant by the valve without variation due to changes in the inlet fluid pressure or head or changes in the pressure drop across the valve.

Various heretofore known efiorts to achieve these ends have not been as successful as is desired since although the valves produced as a result of these efforts have been pressure sensitive and adjustable, they have not maintained the flow rate constant at the selected values therefor. Some such valves have been considered to be more or less successful since they did limit the flow rate to the selected value at one or more points in the design pressure range. Pressure variations away from such points, however, resulted in variations in the flow rate through the valve thereby rendering the valve at least partially unsuccessful.

Such failures, particularly in orifice and metering type valve, it has been found by the present invention, were due in part to the fact that the metering pin or poppet, or the orifice plate of such a valve was biased by a spring or springs, or various other resilient devices, which had linear load rates. That is, the biasing means for the poppet or the orifice plate was such that while being pressure sensitive nevertheless varied linearly with the cs Patent I the metering pin or poppet.

force applied to the resilient means and the displacement thereof had a linear characteristic with respect to the load thereon. This resulted in straight line pressure versus valve displacement movement or valve element characteristics for these valve structures and an obvious ice inability to compensate for the quadratic relationship between the pressure and the flow rate.

Another equally important cause for the lack of success in the prior art devices, it was found by the present invention, was a direct result of the particular profile curvature or envelope which was given to the head of Most such envelopes have been developed experimentally or empirically and the best results favored a profile characteristic which, when plotted, appeared as a straight line on a semi-logarithmic chart.

' A poppet profile or envelope which is a revolution of a pure logarithmic function fails to take into account several of the details which are important for a device of this class as will be developed in detail hereinbelow.

Thus, it will be observed, that although there have been attempts in the prior art to develop adjustable flow control devices having a straight line of pressure versus flow rate characteristic within the design range, these efforts have failed since the poppets were not properly designed and the biasing devices did not have the proper characteristics.

It is, therefore, an important object and feature of the present invention to provide a new and improved adjustable flow controlwherein the fluid flow rate through the control device will be substantially constant, substantially independent of fluid inlet pressure and/ or fluid drop across the device, at least within'the design range of the device.

Another important feature of the present invention is to provide a new and improved adjustable flow control device wherein there is provided a flow orifice and a poppet or metering pin, one of which is biased by a spring having non-linear characteristics and one of which has a revolution profile or limiting envelope which is cooperative with the nonlinear biasing device in such a coordinated manner that the liquid flow rate through the flow control device will be maintained substantially constant irrespective of variations in the fluid pressure drop across the orifice and poppet.

Still another object of the present invention is to provide a new and improved adjustable flow control valve with a new and improved biasing spring for the poppet or the orifice plate which has non-linear characteristics that are proper to maintain the flow rate substantially constant irrespective of variations in fluid pressure.

Another object of the present invention is to provide a new and improved orifice and metering pin type fluid flow control device wherein the envelope of the metering pinor the orifice is such as to provide the device with straight line fluid flow characteristics with respect to' :c'ZnH 0DA= (cbmma 2Y0 Yet another object of the present invention is to provide a new and improved metering valve poppet or metering valve orifice defining member having an envelope following the relation of Yet another object of the present invention is to pro vide a new and improved metering valve poppet or metering valve orifice defining member having an envelope following the relation of Yet another object and feature of the present inven tion is to provide a new and improved fluid flow control i devicewherein the resilient means biasing the, poppet or the orifice defining member follows the law of uan have Yo Yet another object and feature of thepre se'nt inven tion is to provide a new and improved fluid flow control device wherein the resilient means biasing the poppet or the orifice defining member follows the law of for a backing member for the spring. I

Yet another object of the present invention is to provide a new and improved adjustable flow control device wherein the metering pin or poppet is adjustably supported on a pair of springs which are of the double cantilever type and which have their outer ends secured together.

Yet another object of the present invention is to provide a new and improved flow control device of the class described wherein the poppet is resiliently supported on springs backed by contoured backing members having faces which are contoured to give the springs the proper non-linear characteristics desired.

.Yet another object of the present invention is to provide a new and improved adjustable flow control device wherein a profiled poppet is variously displaceable in the aperture of an orifice defining member to control fluid flow for an adjustable substantially constant fluid flow rate without changes due to variations in the pressure.

Yet another object of the present invention is to prov de a new and improved adjustable flow control device wherein the poppet is resiliently supported by a spring having the described non-linear characteristics.

Yet other objects, features and advantages of the present invention will readily present themselves to those skilled in the art from the following detailed description of the present invention and embodiments thereof, from the claims, and from the drawings in which each and every detail shown is fully and completely disclosed as a part of this specification, in which like reference numerals refer to like parts, and in which: I

Figure 1 is a more or less diagrammaticillustration of an adjustable fluid flow control device -embodying the principles of the present invention;

Figure 2 is a transverse fragmental sectional view of the embodiment of Figure lshown as taken substantiallyfa'long the line II-II of Figure l;

'Figurfs 3, '4, s, 6 and '7 areschematic illustrations or various parts of the deviceof Figure 1 and are dimensure in certainregions of fluid pressure and adjusted flow sioned and identified with alphabetical indicia to illustrate various factors which are considered in the design of the device of Figures 1 and 2;

Figures 8 and 8a are graphic examples of the flow versus head or pressure characteristics of adjustable flow control devices embodying the principles of the present invention;

Figure 9 is a more or less schematic illustration of another embodiment of the present invention; and

Figure 10 is a more or lessschematic and diagram: matic illustration of still another formof embodiment of the 'present invention.

As shown on the drawings: 7

There is illustrated in Figures 1 2, 9 and 10 various flow control devices which are adjustable and which are operative to maintain the liquid flow rate therethrough substantially constant at the selected value therefor without variation dueto variations in the fluid pressure at the ...t9' fl r 1Y rt t re b flva t s i e fluid. pressure drop or head drop across the valve structure. Eachof these devices incorporates therein a non-linear resilient backing device, the characteristics of which are fully developed hereinbelow. In addition, each of these valve structures has a poppet or an orifice throat which is profiled to have a curvature in accordance with the laws which are developed hereinbelow. The curved prfiles and the non-linear springs are, however, so coordi- I nated and related that fluid flow through these devices will be maintained substantially constant thereby substantiallyindependent of fluid pressure at least within the control range and substantially independent of fluid presrates outside of the full designirange.

In the embodiment of thezinvention schematically and diagrammatically illustrated in Figures 1 and 2 there is provided a valvehousing having a fluid inlet 11 and a fluid outlet 12. In the fluid inlet 11, or otherwise within the valve housing 10 between the fluid inlet 11 and the fluid outlet12 there is provided orifice defining means such as an orifice block or orifice plate 13 with which there is cooperatively arranged a poppet or metering pin valve'closure means 14. I n

The poppet 14 of the embodiment of Figures 1' and 2 actually includes a poppet plate 15 which is supported at the end of a poppet stem 16 that is secured to a first backing member 17. The poppet plate 15 is reciprocally disposed within the orifice orannulus ls de'fined by the member 13 and adjustably controls fluid flow through thearea between the p'eriph'eral knife edge 19 of the plate 15 and the h roat profile face of the member 13.

The contoured backing member 17 is supported on or secured to' resilient spring means 20 which is also secured to or supported on a second backing plate 21 which is fixed on an adjusting screw 22 threaded through the housing 10 as at 23 and carrying a manual, "or otherwise powered, adjusting knob 24. V v v Thus it may be seen that by proper manipulation of the adjusting knob 24 and therefore the adjusting screw 22, the poppet plate 15 will be resiliently adjustably and reciprocally positioned axially in the orifice 18 in the member 13 to adjust the flow of fluid through the annular area between the knife edge 19 of the orifice plate 15 and the face of the member 13. H r

The face 25 of the member 13 is so contoured that it has a profile or'envelope which follows the laws developed hereinbelow whereby the flow rate will be held substantially constant at any desired adjusted value therefor by resilient axial movement of the poppet :14 thereacross. by guides 2626-26 which are secured to or form a part of the face 25 of the orifice member 13.

flhenon-linear spring assembly 20, in this embodimerit of the invention, comprises a pair of double canti- In its axial movement, the poppet '14is guided backing plates 17 and 21 and are appropriately spaced by and secured together by spacing and mounting blocks 31 and 32 at the ends of the double cantilever type leafs 27 and 28.

The contoured faces 29 and 30 of the backing plates 17 and 21, respectively, are contoured in accordance with the laws developed hereinbelow so that the springs will lie down thereagainst, with increasing fluid pressure at the inlet 11 and increasing fluid pressure drop across the poppet plate 15 and orifice defining member 13, in a manner of increasing the spring load rate which is cooperatively designed with the contour 25 of the orifice defining member 13 so as to accomplish the stated result.

That is, as pressure drop across the poppet and orifice arrangement increases the poppet will be pressed against the springs with greater force so that an increasing part of the contoured surfaces 29 and 36 of the backing members 17 and 21 will back up the double cantilever leaf springs 27 and 28 thereby increasing the spring load rate of these resilient members and increasing the expansion forces thereagainst thereby bucking the increased pressure with increased force.

In the embodiment of Figure 9 all of the same principles apply and the construction is substantially similar to the embodiment of Figures 1 and 2 except that the orifice member 13' is a knife edge plate defining an annulus or orifice 18 and the poppet plate 15' has a contoured face which obeys substantially the same laws as those whichare set out hereinbelow for the orifice throat 25 of the orifice defining member 13. The surface of the poppet head 15' cooperates with the knife edge 19' of the orifice plate 13' in the manner described for the cooperation between the surface 25 and the knife edge 19 in the embodiment of Figure 1 and this surface 25 is designed in coordination with the surfaces 29 and 30 of the backing plates 17 and 21 to cooperate with double cantilever type leafs 27 and 28 of the spring assembly 20 to maintain the fiow rate through the valve substantially constant at any desired flow rate as adjusted and selected through manipulation of the adjusting knob 24 and the adjusting screw 22.

In the embodiment illustrated in Figure the valve structure is operative substantially identical to the operation of the valve structure illustrated in Figure 9 but in this embodiment of the present invention the spring assembly 20' is supported on a backing plate 21' which merely forms a spring rest for the coil spring 20" of variously spaced convolutions. By spacing the corn volutions'of thespring at increasing dimensions in a direction approaching the poppet which is carried on a poppet pin 16' slidably guided in a bearing way 16", the forces of the spring and the spring rate will be continuously increasing as the convolutions successively lie down and become solid by physical abutment with the immediately lower convolution. This spring and such springs as conical springs which will similarly have the convolutions thereof lie down in order will also follow the laws set out hereinbelow for cooperation with the profile 25' bearing guides 26' to maintain the flow rate substantially constant substantially irrespective of pressure and at the adjusted value. Herein, it should be noted that all of the valve structures illustrated in Figures 1, 2, 9 and 10 may be closed by backing off the adjusting screws 22 to a point where the poppet heads 15 and 15' will close the space with the orifice plate members 13 and 13' respectively.

' In Figures 8 and 8a there are illustrated, respectively, an example of a design control range and the extended control range for such valve structures as those illustrated in Figures 1, 9 and 10, and the family of substantially flat flow rate curvesillustrating that adjustable flow control devices embodying the principles of the presrit invention will maintain the flow rate substantially eonstant'at preselected and adjustable desired values subdrop across the orifice and metering pin or poppet head. In Figure 8 it is particularly to be noted that the valve structures are universally operable throughout their en-- tire design control range and are further'operable to maintain the flow rates substantially constant at excessively high or extremely low fluid flow rates in accordance with the extended control range curves therein illustrated.

The control range and the extensions thereof will be more fully understood in connection with the development of the laws for the orifice or poppet profiles and the springs as set out hereinbelow.

Referring now to Figures 1 through 7 generally for the development of these various control laws such as the profile laws and the springlaws, it will be seen that there is illustrated a flow control device consisting essentiallygof a disc moving axially within a profile throat section and resisted by a non-linear spring. The unique relationship between the throat profile and the nonlinear spring resistance of the spring is so developed that an infinitely variable flow controller without inherent error, results. Figure 1 shows one form of such a device. Increasing head drop across the disc displaces I it downstream such that the annular area reduces inversely as the square root of the head, thereby holding the discharge constant. By displacing the spring support axially the discharge is varied and controlled.

The general theory is developed first, resulting in equations for the annular area and the spring law. The actual throat profile equation is then developed, and design data for the device is-determined. Its limitations are worked out and the effects of viscosity, changes in discharge coefiicient and hysteresis, etc., are discussed as a part of thisspecification. While several of the symbols utilized herein are illustrated dimensionally on the drawings, and particularly in Figures 2, 3, 4, 5, 6 and 7, all of the symbols are defined as follows:

A=area of opening between valve head and throat b=width of leaf spring b'=total thickness of guide fins C =discharge coeflicient E=modulus of elasticity e=base of natural logarithms F=pressure force on valve head F minimum design force on valve head g=acceleration due to gravity H =ratio of maximum fluid head to minimum-fluid head h=fiuid head drop across valve head V h =minimum design fluid head loss across valve head =moment of inertia of spring section about neutral axis K =stilfness of spring of length l l=length of spring for load F /2 l=length of disc'support shaft ln=natural logarithm M =moment P=force Q=discharge r==radial coordinate of throat r =minimum throat radius r =disc radius S =maximum fibre stress r s=distance from valve head to throat t=radial distance r-r t =thickness of spring X=function of x v x=axial coordinate ofthroat or valve head x'=position of valve head in throat x =coordinate of spring backing x= dimensionless length ag /l Y'= -function of y Y =positionof spring for h==h y=position of spring T2" yocoordinate of spring backing y dimensionless length yg/Y Z function of z' z=position of spring support z="dimensionles's variable of integration a=constant ot =constant a =constant B=constant B =constant p =constant =specific weight of fluid p 6 'deflection of single spring from minimum design head position ='angular deflection of end of spriiig The theory a the flow controller with reference to Figure 3, the position ofthe disc within the throat is given by x". The setting of the spring is given by z, conveniently measured from a fixed line at a distance I from the minimum throat section. I is also the length of the stern supporting the disc, as shown. The particular spring configuration shown is that of four restrained tip cantilever leaf springs with profiled backing. The backing tends to shorten the spring as it is loaded, thereby stifiening it. The amount of compression of thespring assembly depends upon the dimension y. From the geometry of Figure 3 it will be seen that =r z The product of discharge coefficient, C and annular area, A, is some unknown function of x, say X(x'), i.e.-,

AC =X(x') The spring'positio'ning y is some unknown function Y of the head I: acting across the disc, and is given by h=Y y (3) For the flow to be completely compensated for head change, the discharge Q must be a function (Z) of z, the setting of the spring support, and is 4 9 where the constant {25, with g the acceleration due to gravity, conveniently included in the equation.

The general discharge equation, when velocity of approach is neglected, is

M Q= D viz (5) Substituting Equations 2, 3 and 4 into equation '5 it will be seen that which yields a condition that must be fulfilled by the unknown functions. Taking the natural logarithm (In) of Equation 6, and comparing the same with Equation -1,

To find the coefiicients and exponents, which are herein merely constants, the spring relationship of Equations 3 and 8 yield r hi'at z (10') When h=h the minimum control h'aih letfthe'distance between spring leaves at the center be Y and when h=h H, the maximum design head, let y=0. H is the ratio of maximum head to. minimum head. Then h=h He (11) i which, when solved for y, yields a spring equation for any given head.

Now, using Equations 4 and 8, with the values of 19:5

zZnH it we We The minimum controlled discharge Q is given by the maximum head, h H acting with the minimum area, i.e. the annular area between minimum throat diameter which is the equation for minimum control discharge, and proves out with Equation 5.

Equation 11 is the head-displacement relation that the spring must follow, and Equation 13 yields the annular area required as 'a function of 2:. Equation 12 yields the discharge as a function of position 2 of the spring backing. Hence the existence of the functional relationships for the flow controller without inherent error has been established. The equation of the throat profile is next developed.

Equation for the throakprofile By assuming the discharge coefiicient to be constant in Equation 13, the throat profile equations can be developed.

When experiment yields the variations of C with x, the" throat profile may be recomputed. The reduced equation is zlnH A=Amin e 2Y0 where A is given by mm= o with r the minimum throat radius and r being the disc radius. With fins of total thickness b to guide the disc, Fig. 2, the minimum area is given by mm= -r0or'-ro (1'7) The area A, for any x, is given by Pappus Theorem,

where t arid s areas shown in Fig. 4 the term t -bein'gpositive fora determination of the throat equation for profiled orificesa-s in Fig. 1 and "further being negative for and inserting the Same into Equation it follows that 6 The maximum controlled discharge is then obtained by t substituting x -Y for z in Equation 12, using Equa- A=21r[1 ,i- ]'\/(;v'x) +t (20) tions 14 and 27, considering C constant. A basic design 7r equation in this regard is, Combining Equation 20 with Equation 15, 7 Y ,b, Y

vzlnH Qw= 0Dv fl2v 1r(rl+ (2 v l Z) W 2lnd 27f l'lbH (r r )(r +r b /1r)e -2 r /(x --a,) t

(21) The spring travel Y and the radius of disc r may be i selected to give the required maximum discharge for Forany x an equatlon n x and 1 results that satisfies preselected minimum head ho and head ratio The Equatlon Thls equatlon a however, as X minimum discharge is determined by selection of minichanges- F Envelope of the of curveFa however mum throat radius, r, for given disc radius and maximum yields a continuous profile that satisfies Equations 15 and head n I t a 1* Ifik h P i d i of Equanqn ,ZLYm By moving the spring support to positions where z respecjito x 1 F dlvldmg the resultmg equallon mm is less than zero, control is given under the partial pres- Equauon Ylelds sure range illustrated in Figure 8 where y lz|, which 2Y i 9 maintains the disc within the throat. The discharge is (22) given by Equations 12 and 14 as Solving for x 1 t 2.5 gl iz 7 -s Q=( D )min1/ g 0 o$ 5 (2 a:=:r+ [1- /1 23 e r lnH Y The threshold head range is, from Equations 1 and where the minus sign has been taken before the radical 11 for x =0 so that x'-x becomes small as 2 decreases. Eliminating M i x in Equations 21 and 23 yields the equation of the h=h He Y $z$ 0 (30) envelope, 7 i

2Y -2 -21r Y0 (tlnH)? 1|: (nan)? I w lnH (r1' (7"+T b'/1r) lnH 1 r 2 1 1 Yo (24) which is the throat profile when t is taken positively and Eliminating zin the last two equations, is the poppet profile when t is taken negatively, in terms of x and t. Since r=r it, the cylindrical coordinates 40 Q=(CDA)m1n\/2gh (31) There is a limitation to the value of I, however, which is given by setting the discriminate of Equation 23 equ to zero,

. The envelope solution breaks down for larger values of t, The corresponding maximum values of x and x (26) and Discharge and head range limitations The minimum value of z is zero for control over the whole head range h to h l-l, and the maximum value of z ais'x' -Y as the disc position cannot exceed x' yields the lower limiting line, Fig. 8, for flow control.

Similarly, the setting 2 may be larger than x' -Y for the partial head ranges where y mex The head corresponding to the threshold values of y, i.e. where x'=x' from Equation 11 is --(I'ma:'- 'h=h 'He (32), Eliminating: in this equation and Equations 12 and 14,

ME I III-X7 Q= D )min 9 .3)

This upper extension of the discharge range is shown in Fig. 8.

Factors afiecting accuracy Viscosity effects are very small with this device since the only high velocity is between thesharp-edged or knife-edged portion 19 or 19 and the throat or poppet head.

The change of discharge coefl'lcient as a function of geometry. of opening (x), once it is determined experimentally, can be corrected by adjustment of the throat profile.

Dynamic effects due to high fiow along the disc are small as the area opening is very small compared with the disc area. By adoption of greater disc areas this efiect would be further minimizedr r Y 1 f. "L 3.3

Hysteresis efiects would apply to the spring action only,

and with metal springs should be extremely small, and

even negligible.

Nonlinear spring design and law development The spring form is shown in Figures 1 and 3 as well asFigures 9 and 10, but is considered here principally with respect to the form of spring shown in Figures 1, 3, and 9 as consisting here of four restrained tip cantilever springs, initially flat, and caused to press against the backing such that the stiffness is increased according to Equation 11. The minimum design force, F on the spring is where 'y is the specific weight of fluid. As the force, F, increases linearly with the head, Equationll may be written as V nH F' a The deflection, 6, of one leaf of the spring from the position of minimum force,

acting on the one spring is 1 Y, g 5 '"2mH "F (35) For the minimum design load,

on the single spring, thespring is cantilevered from its full length, l, with the backing touching only at x =0,

Figure 5. With no load on the spring it will be displaced from the 6:0 position a, distance -F l /24EI where E is the modulus of elasticity and I is the section moment of inertia about the neutral axis. a

Following the methods developed by S. P. Clurman, as set out in The Design of Nonlinear Leaf Springs, Trans. A.S.M.E., February 1951, pp. 155-161, a differential equation of the backing profile is developed, based upon beam deflection theory. Considering a point (x y on the backing profile as the last contact between spring and backing for a given load, F, the deflection from no load position isgiven by As the stiffness of a beam varies inversely as the cube of its length,

2 InH 12 Also from Equation 38 F0 Ys 24EI 2lnH Substituting from the last two equations into Equation 36 results in,

i an; 1 r as a 9 a I l @aa de lnH ma 2) p x V ('42) To convert'to a linear equation with constant coeflieients, let a a which reduces Equation 42 to The solution of this equation, for the initial conditions Substituting back for E 3 l y=m[( -)l] This is the dimensionless equation for spring backing profile. From Equation 40, for 6=Y /2, the maximum value of Z, is

The cross-section of the leaf must satisfy Equation 38 Stress analysis of the spring shows that the maximum moment occurs at the end away from the backing. The moment here is determined for the load between f1 2 and when the last contact point on the backing is (x y using the principle ofsuperposition for the two cases shown in Figure 6. Referring to Figure 7, the tip is given an angular deflection, relative to the tangent,

dxo

dz EI 2E1 Obtaining V The maximum value of M occurs for Using Equation 46 v yields MMFQ BH D 8 The maximum fibre stress, S is given by where 2' is the leaf thickness and b its width. Equation 49, plus Equation 38 permit the thickness and width to be expressed in terms of S and I, as

From the foregoing it will be observed that devices embodying the principles of the present invention as by embodying non-linear spring elements obeying the laws hereinabove set forth and having poppet heads or orifice throats profiled in accordance with the law set forth hereinabove, there will be provided adjustable flow control units which are operable to maintain fluid flow substantially constant at the selected values therefor substantially independent of fluid pressure and substantially independent of fluid pressure changes and drops across the valve.

It will also be observed the numerous variations and modifications in the structures set forth, and illustrated, may be made without departing from the true spirit and scope of the novel concepts and principles of this invention. I, therefore, intend to cover all such modifications and variations as fall within the true spirit and scope of the novel concepts and principles of this invent n.

I claim as my invention:

1. In a fluid flow control device, flow orifice means and valve poppet means cooperatively arranged with said orifice means to vary the fluid flow area therebetween, one of said means having a surface of revolution defined by the profile law means having surface of revolution,

and a non-linear resilient spring supporting one of said means and having a non-linear resilient deflection de- Y is the position of the spring for h equals h where h is the fluid head drop across the poppet means and h is the minimum design fluid head loss across the pop- P In is the natural logarithm H is the fluid head drop across the supported means H is the minimum design fluid head loss across the supported means F is the pressure force on the supported means F is the minimum design force on the supported means I is the length of the spring for load F /Z E is the modulus of elasticity I is the moment of inertia of spring section about neutral axis y is the coordinate of spring support x is the coordinate of spring support whereby fluid flow through said device is maintained substantially constant substantially independent of fluid pressure and variations therein.

2. In a fluid flow control device, flow orifice means and valve poppet means cooperatively arranged with said orifice means to vary the fluid flow area therebetween, said valve poppet means having a surface of revolution defined by the profilelaw' 2Yn Y0 ilI'LH 2 n? F -TO WIV (T T) l tlnH 2 ai -v an in which:

x is the axial coordinate of the surface of revolution Y is the travel of the poppet means In is the natural logarithm H is the ratio of maximum design fluid head to minimum design fluid head r is the radius of the orifice means r is the minimum radius of the surface of revolution t is the radial distance rr r is the radial coordinate of the surface of revolution,

and a non-linear resilient spring supporting said valve poppet means and having a non-linear resilient deflection defined by a.

in which:

the

I is the moment of inertia of spring section about neu tral axis y is the coordinate of spring support x is the coordinate of spring support 16 whereby fluid flow through said device is maintained guide fins between the orifice means and poppet means, substantially constant substantially independent of fluid one of said means having a surface of revolution defined pressure and variations therein. by the profile law 3. In a ,fluid flow control device, flow orifice means in which: and valve poppet means cooperatively arranged with said orifice means to vary the fluid flow area therebetween, said flow orifice means having a surface of revolution x is the axial coordinate of the surface of revolution Y is the travel of one of the supported means relative to the other defined by the profile law 15 In is the natural logarithm H is the ratio of maximum design fluid head to minimum T 1 design fluid head 2 l l in 25 0 2 Y ilnH) r is the radius of said means not having the surface of "i H 2 1 g YB revolution r .is the minimum radius of the surface of revolution t is the radial distance rr 1 1 1 tlnH 2 r is the radial coordinate of the surface of revolution "5 Y b is the thickness of the guide fins,

and a resilient spring supporting one of said means and m which: having a non-linear deflection defined by x is the axial coordinate of the surface of revolution Y is the travel of the poppet means relative to the orifice 3 2 means n)%+( 0)% +110 In is the natural logarithm H is the ratio of maximum design fluid head to minimum design fluid head m which: "0 is the radius of the P pp means Y is the position of the spring for h equals h where h 7" iS the minimum radius Of the surface Of revolution .is the fluid head across the poppet means and h is the is the radial distance -"u minimum design fluid head across the poppet means r is the radial coordinate of the surface of revolution, I i h m l logarithm and a non-linear resilient spring supporting said valve H e fi i i ead drop across the supported means poppet means and having a non-linear resilient deflection o 13 the mmlmum deslgn fluld head loss acmss the P d fi d by ported means F is the pressure force on the supported means F is the minimum design force on the supported means Y0 F013 1 (Z2110 2 (71/0 (l z l is the length of the spring for load F /2 2lnh F 24JLI 6 d u 3 0 dxo+yo E is the modulus of elasticity a I is the moment ofinertia of spring section about neutral in which: axis y is the coordinate of spring support Y IS the pos'tlon of the spr'ng for h equals 71 where x018 the coordinate of Spring Support I: is the fluid head across the poppet means and h is the minimum design fluid head loss across the poppet whereby fluid flow through said device is maintained means substantially constant substantially independent of fluid In is the natural logarithm pressure and variations therein. H is the fluid head drop across the poppet means 5. In a fluid flow control device, flow orifice means H is the minimum design fluid head loss across the and valve poppet means cooperatively arranged with said poppet means orifice means to vary the fluid flow area therebetween, F is the pressure force on the poppet means guide fins between the orifice means and poppet means, F is the minimum design force on the poppet means said valve poppet means having a surface of revolution 1 is the length of the spring for load Fi /2 defined by the profile law E is the modulus of elasticity 5 in which: I is the momentof inertla of spring section about neutral x is the axial coordinate of the surface of revolution axis y is the coordinate of spring support x is the coordinate .of spring support Y is the travel of the poppet means In is the natural logarithm H is the ratio of maximum design fluid head to whereby fluid flow through said device is maintained sub- 79 designfluid head stantially constant-substantially independent of fluid presr is the radius of the orifice means sure and variations therein. 7 r r is the minimum radius of the surface of revolution In --a fluid-flow control device, flowor'i'fice means and t is the radial distance r--r valve poppet means cooperatively arranged with said r is theradial coordinate of the surface of revolution orifice means to vary the fluid flow area therebetween, 75 b is the thickness of the guide fins,

17 and a resilient non-linear spring'supporting said valve poppet means and having a non-linear resilient deflection defined by 1 is the moment of inertia of spring section about neutral axis y is the coordinate of spring support x is the coordinate of spring support whereby fluid fiow through said device is maintained substantially constant substantially independent of fluid pressure and variations therein.

6. In a fluid flow control device, flow orifice means and valve poppet means cooperatively arranged with said orifice means to vary the fluid flow area therebetween, guide fins between the orifice means and poppet means, said flow orifice means having a surface of revolution defined by the profile law x is the axial coordinate of the surface of revolution Y is the travel of said poppet In is the natural logarithm H is the ratio of maximum design fluid head to minimum design fluid head r is the radius of the poppet means r' is the minimum radius of the surface of revolution 2 is the radial distance r-r r is the radial coordinate of the surface of revolution b is the thickness of the guide fins,

and a non-linear resilient spring supporting said valve poppet means and having a non-linear resilient deflection defined by I Y is the position of the spring for'h equals k5 where h is the fluid head across the poppet means and h is the minimum design fluid head across the poppet means In is the natural logarithm H is the fluid head drop across the poppet means H is the minimum design fluid head loss across the poppet means F is the pressure force on the poppet means F is the minimum design force on the poppet means 18 l is the length of the spring for load F 2 E is the modulus of elasticity I is the moment of inertia of spring section about neutral axls y is the coordinate of spring support x is the coordinate of spring support whereby fluid flow through said device is maintained substantially constant, substantially independent of fluid pressure and variations therein.

7. In a fluid flow control device, flow orifice means and valve poppet means cooperatively arranged with said orifice means to vary the fluid flow area therebetween, said valve poppet means having a surfaceof revolution defined by the profile law x is the axial coordinate of the surface of revolution,

Y is the travel of the poppet means In is the natural logarithm H is the ratio of maximum design fluid head to minimum design fluid head r is the radius of the orifice means r is the minimum radius of the surface of revolution t is the radial distance rr r is the radial coordinate of the surface of revolution,

and a non-linear resilient coil spring having variously spaced convolutions supporting said valve poppet means and having a non-linear resilient deflection defined by in which: h is the fluid head drop across the poppet means h is the minimum design fluid head loss across the poppet means 7 H is the ratio of maximum design fluid head'to minimum design fluid head e is the base of natural logarithms y is the position of the spring.

In is the natural logarithm Y is the position of the spring for h equals h whereby fluid flow through said device is maintained substantially constant substantially independent of fluid pressure and variations therein.

8. In a fluid flow control device, flow orifice means and valve poppet means cooperatively arranged with said orifice means to vary the fluid flow area therebetween, guide fins between said orifice means and said poppet means, said valve poppet means having a surface of revolution defined by the profile law and a resilient non-linear coil spring having variously spaced convolutions supporting said valve poppet means and having a non-linear resilient deflection defined by uZnH m which:

h is the fluid head drop across the poppet means h is the minimum design fluid head loss across the poppet means H is the ratio of maximum design fluid head to minimum design fluid head e is the base of natural logarithms y is the position of the spring In is the natural logarithm Y is the position of the spring for h equals h whereby fluid flow through said device is maintained substantially constant substantially independent of fluid pressure and variations therein.

9. In a fluid flow control device, flow orifice means and valve popet means cooperatively arranged with said orifice means to vary the fluid flow area therebetween, one of said means having a surface of revolution defined by the profile law in which:

C is the discharge coeflicient A is the area of the opening between the poppet means and the orifice means e is the base of natural logarithms x is the position of the poppet means relative to the orifice means In is the natural logarithm H is the ratio of maximum design fluid head to minimum design fluid head Y is the travel of the supported means,

and a non-linear resilient spring supporting one of said means and having a non-linear resilient deflection defined by I in which:

h is the fluid head drop across the'poppet'means h is the minimum design fluid head loss across the poppet means H is the ratio of maximum design fluid head to minimum design fluid head eis the'baseof 'natural logarithms y is the "position "of the spring In is the natural logarithm Y is the position of the spring for h equals h whereby fluid flow through said device is maintained substantially constant substantially independent of fluid pressure and variations therein.

10. In a fluid flow control device, flow orifice means and valve poppet 'means cooperatively arranged with said orifice means "to vary the fiuid flow area therebetween, said valve poppet means having a surface of revolution defined by the profile law in which:

C is the discharge eoeflicien't A is the area of the opening between the poppet means and the orifice means e is the base of natural logarithms x' ;is the position of the poppet means relativeto the orifice means In is the natural logarithm H is the ratio of maximum 'designfluidhead to minimum design fluid head Y is the travel of the vsupported means,

and a none-linear resilient spring supporting said valve poppet means and having a non-linear resilient deflection defined by h=h He in which:

h is the fluid head drop across the poppet means h is the minimum design fluid head loss poppet means His the ratio of maximum design fluid head to minimum design fluid head e is the base of natural logarithms y is the position of the spring In is the natural logarithm Y is the position of the spring for [1 equals h whereby fluid flow through said device is maintained substantially constant substantially independent of fluid pressure and variations therein.

References Cited in the file of this patent UNITED STATES PATENTS 1,658,547 .Aseltine Feb. 7, 1928 1,904,337 Turner Apr. 18, 1933 1,944,088 Linderoth -Jan. 16, 1934 2,086,321 Kudo July 6, 1936 2,117,891 'Kalin May 17, 1938 2,399,938 Pett May 7, 1946 Obermaier Mar..18, 1958 OTHER REFERENCES A.S.M.E. Transactions (Clurman), vol. 73, pub. by .A.S.M.-E., 1951, pp. -161. ,(Copy in Scientific Library.)

across the 

